Growth hormone (GH) is a hormone that is produced by the pituitary gland and plays an important role in growth and development. The level of GH in the body can be measured by a growth hormone test, which is a blood test used to evaluate the function of the pituitary gland. In this article, we will discuss the growth hormone test, its purpose, procedure, and results.
Purpose of Growth Hormone Test
The growth hormone test is primarily used to diagnose disorders related to the pituitary gland, such as growth hormone deficiency and acromegaly. Growth hormone deficiency is a condition in which the pituitary gland does not produce enough growth hormone, while acromegaly is a condition in which the body produces too much growth hormone. The growth hormone test is also used to monitor the effectiveness of growth hormone replacement therapy in individuals with growth hormone deficiency.
The growth hormone test is a blood test that is performed in a laboratory or a healthcare provider’s office. The procedure involves the following steps:
- Fasting: The individual is asked to fast for 10 to 12 hours before the test. This means that they should not eat or drink anything except water during this period.
- Baseline blood sample: The healthcare provider will take a blood sample to measure the individual’s baseline GH level.
- Administration of GH stimulant: The individual is given a GH stimulant, such as insulin, clonidine, or arginine. The stimulant is given through an injection or orally.
- Blood samples: The healthcare provider will take several blood samples over a period of 2 to 3 hours to measure the individual’s GH level in response to the GH stimulant.
Results and Interpretation
The results of the growth hormone test are typically reported as the peak GH level that occurs after the administration of the GH stimulant. The normal range of GH level varies depending on the age and sex of the individual. The following table shows the normal ranges for GH level in adults and children:
|Age group||Normal range (ng/mL)|
|Children||Less than 10|
|Adults||Less than 5|
If the peak GH level is less than the normal range, it may indicate growth hormone deficiency. If the peak GH level is higher than the normal range, it may indicate acromegaly or other disorders related to the pituitary gland.
Q. How long does the growth hormone test take?
A. The growth hormone test typically takes 2 to 3 hours to complete.
Q. Is fasting required for the growth hormone test?
A. Yes, fasting for 10 to 12 hours is required before the growth hormone test.
Q. Is the growth hormone test painful?
A. The growth hormone test involves a needle prick, which may cause some discomfort. However, the discomfort is usually mild and brief.
Q. Can medications affect the results of the growth hormone test?
A. Yes, some medications, such as glucocorticoids and dopamine agonists, can affect the results of the growth hormone test. It is important to inform the healthcare provider of all medications that the individual is taking before the test.